Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description discloses critical behavioral traits beyond annotations: invoke runs uninstalled MCPs one-off, returns connect/checkout links on auth/payment failures, and requires owner/admin for writes. No contradiction with annotations (readOnlyHint=false, destructiveHint=false). This gives the agent operational details needed to anticipate side effects.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single dense paragraph (~300 words) with no headers or bullet points. It is front-loaded with the main purpose but becomes a wall of text, repeating invoke/install advice and mixing the MCP marketplace and prompt library topics. While the content is valuable, the structure hampers quick scanning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers most actions, permissions, prompt library, and even error flows (connect/checkout links). However, it omits the `resume` action entirely and provides no details on output formats or pagination, which are important for a tool with no output schema. It is highly complete for core usage but not exhaustive.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema coverage, the description compensates by explaining key parameters: `action` (all enumerated values), `tool_id` (used by invoke), `arguments`, and prompt parameters like `prompt_slug`, `prompt_vars`, and `prompt_body`. However, many parameters (limit, immediate, tier_slug, cancel_reason, etc.) are never mentioned, leaving gaps. Still, it adds substantial meaning for the core flow.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It also explains the core flow (search → describe → invoke) and distinguishes marketplace actions from the sibling tools (e.g., report_bug, toolkit_info). This is a specific, verb-driven purpose that leaves no ambiguity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives explicit when-to-use guidance, e.g., 'Use install only to make an MCP PERMANENT in the active toolkit... prefer invoke for a single/occasional use.' It also defines the core flow and states that writes require workspace owner/admin. This clearly tells an agent when to use each action versus alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.